Sounds like it is Stress related. The worst part about it is that you get more stressed by the symptoms and it becomes a cycle. Try some physical activity and do your best to ignore the symptoms. They will pass. I am by no means an MD but I have had similar issues. The Drs cave me a clean bill of health, but I felt that something was wrong.
Good luck
Bitter taste can be because of acid reflux from the stomach. You can get a physical done from a doctor and then proceed